fix: improve import controller deletion reconcile

[anmazzotti]

What this PR does / why we need it:

Fixes #2059

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

Checklist:

• squashed commits into logical changes
• includes documentation
• adds unit tests
• adds or updates e2e tests

[anmazzotti]

/backport v2.14.0 release/v0.26

[anmazzotti]

/backport v2.13.3 release/v0.25

[rancher-backport-assistant]

Not creating backport PR, there was an error running git am -3:

Applying: fix: improve import controller deletion reconcile
Using index info to reconstruct a base tree...
M	internal/controllers/import_controller.go
Falling back to patching base and 3-way merge...
Auto-merging internal/controllers/import_controller.go
CONFLICT (content): Merge conflict in internal/controllers/import_controller.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
Patch failed at 0001 fix: improve import controller deletion reconcile